In many applications, especially satellite communications, it is important to maximize the strength of signals received, for example, by a microwave antenna feed horn. This requires that the antenna be pointed precisely at the incoming beam even though the transmitter may not be stationary. An electronic autotracking antenna provides for autotracking on a received signal, that is, it can be used to develop signals indicating whether or not the antenna's boresight axis is aligned with the direction of the incoming signal wave front beam. To perform this function, the antenna feed is electronically switched to sequentially provide four slightly different beam receiving positions. The direction of arrival of the received signal can be deduced from the relative signal strengths in the four beam directions. This type of action is often called "sequential lobing".
The switching is typically done at a rate of less than 400 Hz which is slow relative to the signal frequencies but fast enough to allow for effectively constant correction of the antenna position. Such a system using two mode switching arms for the TE.sub.21 mode and two mode switching arms for the TM.sub.01 mode to "squint" the antenna in four orthogonal directions is well known. Such prior systems require a significant amount of hardware not otherwise required for the data transmission, limit the bandwidth capacity of the antenna and are effective only for one sense of circularly polarized signals.